The present invention relates to a novel adamantane derivative and a process for producing the same. More specifically, the present invention relates to novel (monohalogen-substituted methyl) (adamantyl group-containing alkyl)ethers which are useful as a modifying agent for a resin for a photoresist and a dry etching resistance-improving agent in the photolithography field, agricultural and medical intermediates and other various industrial products and a process for efficiently producing the same.